Which pathogen is responsible for syphilis?

Which of the following principles should be followed to stay free from Sexually Transmitted Infections $(STIs)$?

Which of the following is not included in $STI$?

Which of the following $STDs$ is not caused by a bacterium?

The $V.D.R.L.$ test is performed for which of the following?

$A$ : Diseases or infections which are transmitted through sexual intercourse are collectively called sexually transmitted diseases $(STDs)$.
$R$ : $STDs$,if not properly treated,may lead to pelvic inflammatory diseases,abortion,stillbirth,ectopic pregnancies,infertility,or even cancer of the reproductive tract.